staging/lustre: Get rid of object update code

Object update was originally planned to be used for cross-server
updates, so nothign to do with the client. The idea was
later significantly reworked anyway so even wire structs should
not be retained.

This gets rid of update_cmd_t, UPDATE and UPDATE_REPLY rpc and
corresponding subcommands, swabbig logic and such.

Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>